US 8019442 B1
In one embodiment, an assembly for conducting pulses from an implantable pulse generator, comprises: at least one percutaneous lead comprising terminals and at least two groups of electrodes, each group of electrodes possessing an intra-group electrode spacing; a frame member comprising first and second arms, the frame member comprising an inner lumen for removably housing the at least one percutaneous lead, each arm of the first and second arms comprising a plurality of apertures that are spaced according to the intra-group electrode spacing to allow conduction of electrical pulses from the electrodes of the at least one percutaneous lead to tissue of the patient when the lead is positioned within the frame member; and a spring member that is connected to the frame member for maintaining the first and second arms of the frame member at a predetermined distance in the absence of an external force on the spring member.
1. A method of explanting a percutaneous lead from the epidural space of a patient, wherein electrodes of the percutaneous lead are maintained in the epidural space of the patient at fixed relative positions by a frame member and a spring member, the frame member comprising first and second arms with the spring member maintaining the first and second arms at a predetermined distance in the absence of an external force on the spring member, and the percutaneous lead is looped through first and second arms of a frame member such that distal and proximal ends of the percutaneous lead are exterior to the epidural space of the patient, wherein the percutaneous lead comprises an interior lumen that extends along a substantial length of the percutaneous lead, the method comprising:
accessing the percutaneous lead within the patient;
inserting, after performing the accessing, a strengthening wire member through the lumen of the percutaneous lead such that the strengthening wire member is looped through the frame member;
placing a flexible surgical tool over the distal and proximal ends of the percutaneous lead and advancing the surgical tool until the surgical tool accesses the epidural space of the patient; and
applying a pulling force to the percutaneous lead, wherein the pulling force causes the frame member to be brought into contact with the surgical tool, and the contact of the frame member with the interior wall of the surgical tool causes the frame member and spring member to collapse to assume a profile to allow the frame member and spring member to be withdrawn through the surgical tool.
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This application claims the benefit of U.S. Provisional Application No. 60/862,909, filed Oct. 25, 2006, the disclosure of which is incorporated herein by reference.
The present application is generally related to an assembly kit for creating paddle-style lead using one or several percutaneous leads and method of lead implantation.
Application of electrical fields to spinal nerve roots, spinal cord, and other nerve bundles for the purpose of chronic pain control has been actively practiced for some time. While a precise understanding of the interaction between the applied electrical energy and the nervous tissue is not fully appreciated, it is known that application of an electrical field to spinal nervous tissue (i.e., spinal nerve roots and spinal cord bundles) can effectively mask certain types of pain transmitted from regions of the body associated with the stimulated nerve tissue. Specifically, applying electrical energy to the spinal cord associated with regions of the body afflicted with chronic pain can induce “paresthesia” (a subjective sensation of numbness or tingling) in the afflicted bodily regions. Thereby, paresthesia can effectively mask the transmission of non-acute pain sensations to the brain.
It is known that each exterior region, or each dermatome, of the human body is associated with a particular longitudinal spinal position. Thus, electrical stimulation of spinal nerve tissue must occur at a specific longitudinal location to effectively treat chronic pain. Additionally, it is important to avoid applying electrical stimulation of nerve tissue associated with regions of the body that are unaffected by chronic pain. Positioning of an applied electrical field relative to a physiological midline is also important.
Percutaneous leads and laminotomy leads are the two most common types of lead designs that provide conductors that deliver stimulation pulses from an implantable pulse generator (IPG) to distal electrodes adjacent to the nerve tissue. As shown in
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Some representative embodiments are directed to an assembly kit for receiving one or several percutaneous leads. The assembly kit includes a frame member through which the percutaneous leads are threaded. The frame member comprises first and second arms for receiving the percutaneous leads. In each arm, the frame member comprises apertures that correspond to the positions and spacing of the electrodes of the percutaneous leads. During assembly, the percutaneous leads are advanced through the frame member until the electrodes are exposed through the apertures. A spring member is attached to the frame member to provide a mechanical bias to retain the arms with their leads at a desired width when an external compressive force is not applied to the spring member. Also, a thin film member is preferably disposed between the first and second arms to prevent tissue in-growth between the two percutaneous leads after implantation.
During the implantation process, a suitable hollow-channel insertion tool is inserted within the epidural space of the patient according to one representative embodiment. The distal end with the spring member is inserted into the suitable hollow-channel insertion tool. The shape of the spring member allows the spring member and the arms of the frame member to be inwardly compressed to assume a relatively small profile. The compression of the spring member and the frame member enables the implantation to occur through a relatively small insertion tool thereby reducing the trauma to the patient. The spring member, the frame member, and the lead(s) are advanced into the epidural space through the insertion tool. Accordingly, removal of bone tissue is not required. Upon exiting the insertion tool, the spring member causes the arms of the frame member to be separated by the desired amount of space and thereby cause the electrodes of the stimulation lead(s) to be positioned in a manner similar to a paddle lead. The stimulation leads can then be utilized for spinal cord stimulation and the relative positions of the electrodes will remain fixed. Also, the field applied by the electrodes will be substantially unidirectional.
The foregoing has outlined rather broadly certain features and/or technical advantages in order that the detailed description that follows may be better understood. Additional features and/or advantages will be described hereinafter which form the subject of the claims. It should be appreciated by those skilled in the art that the conception and specific embodiment disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes. It should also be realized by those skilled in the art that such equivalent constructions do not depart from the spirit and scope of the appended claims. The novel features, both as to organization and method of operation, together with further objects and advantages will be better understood from the following description when considered in connection with the accompanying figures. It is to be expressly understood, however, that each of the figures is provided for the purpose of illustration and description only and is not intended as a definition of the limits of the appended claims.
Referring now to
Assembly kit 200 further comprises spring member 203 that is attached to frame member 202. Spring member 203 may be permanently attached to frame member 202 during fabrication of these components or may be fabricated as a separate component for attachment by a surgeon. When assembled as shown in
One advantage of allowing the surgeon to attach spring member 203 during the implantation procedure is that multiple sets of spring members 203 could be provided with each set having different spring characteristics. The surgeon could select a spring member 203 having a greater spring constant if assembly kit 200 does not sufficiently expand in the epidural space using another spring member 203 due to fibrosis or other tissue obstructions. Additionally, to prevent fibrosis or other tissue in-growth from occurring after implantation, thin membrane 205 is provided between the arms of frame member 202. Thin membrane 205 can be fabricated from a low durometer, elastic Carbosil material as an example. By utilizing membrane 205, kit 200 can be more readily explanted if subsequently necessary.
Spring member 203 is also preferably fabricated from PEEK material which possesses a spring memory characteristic. Other suitable biocompatible, biostable polymers can be employed such as PEKK. If spring member 203 is fabricated as a separate component from frame member 202 as shown in
Spring member 203 is also preferably shaped so that when the end of spring member 203 encounters the inner wall of an insertion tool, the contact force tends to “pinch” spring member 203 thereby providing a compressive force to spring member 203. In response to the compressive force, spring member 203 collapses the arms of frame member 202 thereby allowing kit 200 to assume a profile that allows kit 200 to be advanced through the insertion tool.
Any suitable percutaneous lead(s) 201 can be employed within kit 200 provided that the electrode spacing of the lead(s) 201 corresponds to the spacing of apertures in frame 202. In one embodiment, a respective percutaneous lead is inserted within each arm of frame member 202. An example of a suitable commercially available lead for assembly kit 200 is the Axxess® lead available from Advanced Neuromodulation Systems, Inc. (Plano, Tex.). To retain each percutaneous lead 201 within frame, retention clips 207 are provided. Additionally, retention clips 207 facilitate the removal of frame member 202 from the epidural space when leads 201 are explanted.
In one embodiment as shown in
Also, to facilitate explantation, the proximal portion of frame member 202 is shaped at locations 206 a and 206 b to contact the inner wall of the insertion tool as shown in
After insertion of the strengthening wire member and positioning of the open channel tool, the surgeon “pulls” on the lead and the strengthening wire member. The pulling force causes the lead, frame member 202, and spring member 203 to move up to the distal end of the tool. When the proximal end of frame member 202 contacts the inner wall of the tool, the resulting force pushes against locations 206 a and 206 b and the force is transferred from the arms of frame member 202 to spring member 203. The transferred force tends to elongate the frame and spring member 203 thereby compressing spring member 203 and bringing the arms of frame 202 together. Accordingly, the profile of frame 202 is reduced thereby allowing the kit 200 to be received within the open channel of the tool for removal from the epidural space.
In such a procedure, the benefit of looping the lead within the kit 200 is realized. Specifically, the looping of the lead enables the strengthening wire member to follow the entire perimeter of frame member 202 and spring member 203. Accordingly, a sufficient amount of force can be readily applied to ensure that spring member 203 is compressed to allow the withdrawal of the kit 200 through the surgical tool. Additionally, it shall be appreciated that explantation procedures according to representative embodiments involve relatively little complexity and do not require overly delicate manipulations.
Although representative embodiments and advantages have been described in detail, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the appended claims. Moreover, the scope of the present application is not intended to be limited to the particular embodiments of the process, machine, manufacture, composition of matter, means, methods and steps described in the specification. As one of ordinary skill in the art will readily appreciate from the disclosure that processes, machines, manufacture, compositions of matter, means, methods, or steps, presently existing or later to be developed that perform substantially the same function or achieve substantially the same result as the corresponding embodiments described herein may be utilized. Accordingly, the appended claims are intended to include within their scope such processes, machines, manufacture, compositions of matter, means, methods, or steps.